Production of wrought iron direct from electrolytic iron



July 3, 1928.

R. D. PIKE PRODUCTION OF WROUGHT IRON DIRECT FROM ELECTROLYTIC IRON Filed June 30, 1924 [12 van tor. Robert D. Pike. 2 0M141 I {it Patented July 3, 1928.

UNITED STATES ROBERT D. PIKE, OF SAN FRANCISCO, CALIFORNIA.

PATENT OFFICE.

:enonuCTron or WROUGHT IRON DIRECT neon: ELECTROLYTIC more.

Application filed June 30, 1924. Serial No. 723,234.

This invention relates to the production of wrought iron direct from electrolytic iron. In a co-pending application filed by myself and George H. West jointly, of even'date herewith, there is disclosed a process for the making of pure iron from broken or pow-. dered electrolytic iron cathodes.

My present invention has for its object to make wrought iron articles of a special high rade direct from electrolytic iron cathode 5168135 without breaking the same into smaller particles. By eliminating the breaking-up step, I reduce handling costs, and also reduce the danger of contamination by oxygen and other gases, because such gases are given a greater chance for action the 1 greater the surface exposed. My present invention also possesses other-unique advantages, notably the production of wrought iron sheets, plates, or other objects made up of substantially continuous lamina; of pure iron and slag. The advantage of slag laminm is well recognized in wrought iron because these reduce the conduction of electric currents which cause electrolytic corrosion; but in wrought iron as produced by present processes, such slag laminae are broken and irregular, whereas in the wrought iron produced by my present process the laminae are substantially continuous and regular. Furthermore, the relative-thickness of the iron and slag laminae may be changed at will and the'slag laminae may be substantially eliminated if desired.

A further object of my invention is to sheets and to build up large iron objects, as

for example, billets, bars, pipe, skelp, etc.,

by welding and working the original cathode sheets with suitable fluxes or, deoxidizing additions, or both; and in carrying out this .object I may start with one or several cathode sheets.

I am aware of the fact that it was heretofore been proposed to produce iron sheets by rolling electrolytic iron plates after they have been stripped from the cathode starting sheet, but I have found that iron produced in this way will seldom be sound,'because it will usually contain intercrystalline cracks which are coated with oxide or other compound which revents the iron from becoming welded. am not aware of an prior method capable of producing soun merchantable iron by welding together separate stages of the present process and product.

F ig, 1 shows an electrolytic iron cathode sheet 1n perspective.

Fig. 2 shows a transverse cross-section of bundle of sheets assembled in an annealing Fig. 3 represents a rolled sheet with exaggerated representation of laminae.

The electrolytic iron cathode sheets 1, Fig. 1, when strip ad from the cathode are about thi'c but may be as thick as 1". The side which adhered to the cathode is smooth but the side on which the deposit was made is rough. Sheets may be of any desired size, but 24"wide by 30" long is a convenient size. The sheets when strlpped are brittle, and should be handled with care.

2 is an annealing box of nichrome or similar material which has inside dimensions about larger all around than the cathode surface of this sheet is then dusted with a fairly pure form of powdered iron ore so as to substantially fill the" depressions on the surface and make a fairly smooth bedding for the next sheet. Mill scale can be mixed with the iron ore so as to bring up the iron oxide content. A considerable variation in the quantity and quality of the iron ore is permissible, depending on the results desired, and it may be omitted entirely or some prepared form of slag materials may be used to replace it in whole or in part. In producing laminated wrought iron the end sought is to produce slag laminae which will have substantially the same chemical properties as those slags occurring in the best grades of wrought iron.

The slag laminae must not be so thick as to mounds which occur on the rough side of the sheet, and which will comeinto welding v contact with the smooth .face of the sheet above when the whole is passed through the rolls in a subsequent step' of the process;

oxides formed will become part of the slag laminm.

Whenthe sheets have been placed in the annealing box as described, the marginal The bundles may now spaces are filled with iron oxide and the cover isput on the box. The transverse section then appears as Fig. 2, in which 3 is the powdered material t is the cathode sheet, 5 is the cover of the annealing box.

The annealing box is then put in a furnace having a reducing atmosphere and the tem-' perature raised as quickly as possible to about 1832 F. and held at this temperature for about one hour. At this temperature the hydrogen which is driven off from the oathode sheets causes a reduction of the iron oxide between the plates, leaving a pure carbon-free iron mixed with the slagging and other added ingredients. The same reduction may also be assisted by the reducing atmosphere in the furnace, which penetrates into the boxes to some extent, or by the addition of metallic deoxidizers, or hydrogen or illuminating gas introduced into the boxes.

The furnace is now cooled while maintaining a reducing or substantially neutral atmosphere, and the bundles of sheets are carefully removed from the annealing boxes.

be sheared longitudinally to form more convenient sized billets.

The next step is to heat the billets to a welding heat in a furnace which preferably has a neutral or reducing atmosphere. In the case of pure iron such welding heat is between 2650915. and 27 00 F. While at this 7 temperature throughout their mass, the billets are removed from the furnace and quickly passed through rolls, which completes the welding process.

The preferable method is to continue the reduction of the billets in a direction perlaminae, so that eventually a sheet or pipe skelp is produced, similar to 6, which is formed of a series of substantially regular laminae of iron and slag.

My process permits of forming such sheets 1 or pipe skelps of practically chemically pure iron-more pure than is possible by any known processand as the iron exists in laminae it will be readily seen that the product possesses a unique degree of resistance to corrosion, making it highly suitable for manufacture of pipe and sheets. In addition, my process permits of creating in the iron laminae a wide range of alloys of differtomes? ent chemical and mechanical properties, by difiusion into the iron during the heating and welding, of the desired alloying ingredient.

I have also found that in a certain modification of my process it is possible to do away with the annealing step, and to combine both heating steps into one. This is done by adding suflicient deoxidizer, such as powdered silicon, or ferro-silicon, powdered ferro-manganese, or powdered aluminum, to the oxide of iron which is placed between the electrolytic iron sheets, together with a slight excess of the deoxidizing metal to take care of any superficial oxide of iron which may occur on the surface of the sheets. This mixture of iron oxide and powdered metallic deoxidizer is placed between the electrolytic iron sheets as described above, several sheets being piled one'on top of the other, and the whole being then secured in a bundle by any suitable means, as for ex ample by binding with wire. This bundle is then placed in a furnace, preferably having a neutral or reducing atmosphere and heated as rapidly as possible to welding heat, or to high enough heat as to cause reaction between the iron oxide and the deoxidizing metal employed. This reaction will in itself generate considerable heat, particularly if the reducing agent be composed in whole or in part of powdered aluminum, and this heat supplementing the heat of the furnace will cause an effective welding of the sheets. The deoxidiser which is employed combines with the oxygen, forming a slag material. In some cases it may be deemed desirable to have the oxide mixture with the deoxidizer contain an excess of iron oxide, so that the slag material which is formed may form compounds with iron oxide, forming as for example ferrous silicates. This variation of the process has the advantage of doing away with the annealing step, and of cementing the sheets of electrolytic iron together with a pure oxygen-free iron combined with a certain amount of slag.

If desired the material which is placed betweenthe sheets may be sand or similar slag-forming materials which are ordinarily used as fluxes in the welding of iron. Sand will form ferrous silicate with the iron oxides which are present at the high temperature of the process and these silicate substances will aid in the welding of the sheets. My invention contemplates the working of the sheets at or near welding heat by suitable mechanical means until a sound metal is produced. If the slag-forming or fluxing material, as for example sand with or without a little borax and without metallic deoxidizers, is employed to assist the welding of the iron by virtue of the formation of a fluid ferrous silicate slag which absorbs the iron oxide from the surface of the cracks and the surface of the metal and thus permits these cracks to be welded into a sound metal, the addition of iron oxide between the sheets may be omitted. The object of the process in any of its modifications is toremove iron oxide as such from all surfaces within the mass, so that these surfaces may become welded together. This is accomplished either by forming a; slag with the iron oxide or by reducing it to the metal by means of gaseous or metallic reducing agents. If the latter are employed slags are necessarily formed in .situ which also combine with iron oxide.

For example, if silicon be employed, silica is formed; and th s can combine with any more iron oxide present to form ferrous S11].-

4 cates which constitute a fiuid slag at the temperatures employed. The Working of the mass by rolling or hammering at or near welding heat is then depended upon to work the fluid slags which are formed into all cracks, thus permitting these to become welded.

My process 1s susceptible to many changes in detail without departing from the spirit of my invention, which I believe is fundamentally new in the art of making ferrous metals.

What I claim and desire Letters Patent is; I

'1. As an article of manufacture, wrought iron consisting of substantial lamina'tions of electrolytic iron in cathode sheets, with intermediate laminae of slagi I i 2. The process of manufacture of wrought :to secure by in stacking sheets of the reduced to metallic iron by the liberated hydrogen, then heating the stack to welding heat, and welding.

4. The process of manufacture of wrought iron from electrolytic iron, which consists same and bedding between each sheet an oxide iron, then annealing the stack in .an inclosed space so that the oxides of iron in the stack will be reduced by the liberated hydrogen, then heating the stack'to welding heat, and weld- 111 d. The process of manufacture of wrou ht iron from electrolytic iron which consists in stacking sheets of the latter, bedding a slag forming material between each sheet, heating said stack to welding heat, and Welding.

6. The process of manufacture of wrou ht iron from electrolytic iron which consists in stacking sheets of the latter, bedding a slag-forming materlal between each -sheet which will form a fluid slag with the iron oxide present, heating said stack to 'welding heat and welding by application of mechanical pressure. 4

ROBERT D. PIKE; 

